Should each AI icon file be taken to Photoshop up to 100 times to convert 100 AI icons to PNG files at a size of 64×64? Or is there a shorter/faster way?
If you're running on Adobe CC 2015 or later, you have the option to use the Export for Screens feature (Command + Option + E or
File > Export > Export for Screens... ). Just a side note, this approach assumes that the icons you want to export all live in the same Illustrator document and are all on their own Artboard:
Execute the Export for Screens command with Command + Option + E or
File > Export > Export for Screens... and set the export options in the dialog box:
Setting up the document before exporting will be the critical step in using this tool. Be sure that your Artboards are the same dimensions so you can effectively resize all artboards in the same command. Conversely, if there are Artboards of variable size in the document, Export for Screens gives the option to export out 'All' or a 'Range' of Artboards from the file.